GE Multilin 745 Instruction Manual

S4 Elements745Transformer Management RelaySetpointshttp://www.GEindustrial.com/multilin5ñ46 GE MultilinOver and above the standard harmonic inhibit feature programmed above, the 745contains a harmonic inhibit feature which is in service only during energization and/or sympathetic inrush. De-energization and energization of the transformer isdetected by any of the following three methods:1. With energization sensing by current enabled, all currents dropping below theminimum energization current indicates de-energization; any current exceedingthe minimum energization current indicates energization. This method is theleast reliable method of detecting energization, since an energized andunloaded transformer will be detected as being de-energized if this method isused alone.2. With energization sensing by voltage enabled, the voltage dropping below theminimum energization voltage indicates de-energization; any current exceedingthe minimum energization current indicates energization.3. With ëbí auxiliary contacts from all switching devices (which can be used toenergize the transformer) connected in series to a logic input and assigned tothe BREAKERS ARE OPEN setpoint, the contacts closed indicates de-energization;any current exceeding the minimum energization current indicates energization.Energization inhibit settings are put in service upon detection of de-energization.Upon energization, the energization inhibit duration timer is initiated and thesettings are removed from service when the time delay elapses. The energizationinhibit feature may also be put in service during sympathetic inrush. The onset ofsympathetic inrush is detected via a close command to the parallel transformerswitching device connected to a logic input, assigned to the PARALL XFMR BRKR CLSsetpoint. Energization inhibit settings are put in service when the contact closes.Upon signal removal, the energization inhibit duration timer is initiated and thesettings are removed from service when the time delay elapses.In a breaker-and-a-half scheme, where current can be present in the CTs withoutbeing present in the transformer winding, it may be necessary to use the ParallelTransformer Breaker Close contact to initiate Energization Inhibit.ï ENERGIZATION INHIBIT PARAMETERS: Select ì2ndî to compare the 2 ndharmonic current against HARMONIC INHIBIT LEVEL. Select ì2nd + 5thî to use theRMS sum of the 2 nd and 5 th harmonics.ï HARMONIC AVERAGING: Select ìEnabledî to use the three-phase average ofthe harmonic current against the harmonic inhibit setting.ï ENERGIZATION INHIBIT LEVEL: Enter the level of harmonic current (2 nd or2 nd + 5 th ) above which the percent differential element is inhibited fromoperating. This setting will often need to be set significantly lower than theHARMONIC INHIBIT LEVEL, especially when used with the ìParallel Xfmr BkrClsîlogic input function for sympathetic inrush.ï ENERGIZATION INHIBIT DURATION: Enter the time delay from themoment of energization (or the end of the parallel breaker close command)before the energization inhibit feature is removed from service.ï ENERGIZATION SENSING BY CURRENT: Select ìEnabledî to detect de-energization by the level of all currents dropping below the minimumenergization current.ï MINIMUM ENERGIZATION CURRENT: Enter the current level below whichthe transformer is considered de-energized (energization sensing by currentenabled), and above which the transformer is considered energized (anyenergization sensing enabled).ï ENERGIZATION SENSING BY VOLTAGE: Select ìEnabledî to detect de-energization by the level of the voltage dropping below the minimumenergization voltage. This setpoint is displayed only if S2 SYSTEM SETUP !"VOLTAGE INPUT ! VOLTAGE SENSING is ìEnabledî.ï MINIMUM ENERGIZATION VOLTAGE: Enter the voltage level below whichthe transformer is considered de-energized (when ENERGIZATION SENSING BY